Huawei Quidway S3700 Series Configuration Manual page 349

Quidway S3700 Series Ethernet Switches
Configuration Guide - Reliability
l
----End
Issue 01 (2011-10-26)
NOTE
On each switch to be configured with a delay mode in a VRRP backup group, it is recommended
to configure backup switchs with the immediate preemption mode (whose delay time is 0
seconds) and configure the master switch with the preemption mode (whose delay time is
specified). Configuring the delay time for the master switch can ensure that the original primary
link has enough time to restore and work stably, and then switch back. At the same time, the
backup link works normally. If the data is switched back to the original primary link, the
application is not affected.
For VRRP6, run the following commands:
1. Run:
system-view
The system view is displayed.
2. Run:
interface interface-type interface-number
The interface view is displayed.
3. Run:
vrrp6 vrid virtual-router-id preempt-mode timer delay delay-value
The delay time of preemption is configured on the switch in the VRRP6 backup group.
By default, the preemption mode is enabled and the delay time of preemption is 0
seconds, indicating immediate preemption. In immediate preemption mode, a backup
router becomes the master router when detecting that its priority is higher than the
priority of the master router. Then, the original master router becomes a backup router.
After the delay time of preemption is set, a backup router can be delayed for a specified
period to preempt the master router.
You can run the vrrp6 vrid preempt-mode disable command to adopt the non-
preemption mode on the switch of the VRRP6 backup group. In non-preemption mode,
after a certain switch becomes the master router in the backup group and works
normally, another switch cannot preempt the master router even if its priority is set to
a value higher than that of the master router.
When the IPv6 address owner recovers from a fault, the router immediately becomes
the master router despite the set delay time. The preemption delay refers to a period
during which a backup router waits for preempting the master router, whereas an IPv6
address owner is irrelevant to the preemption delay. In a VRRP6 backup group that
needs to be configured with the preemption delay, the master router cannot be
configured as the IPv6 address owner.
You can run the undo vrrp6 vrid preempt-mode command to restore the default
preemption mode.
NOTE
To configure the preemption mode for each switch in a VRRP6 backup group, you are
recommended to configure the immediate preemption mode on each backup router by setting
the delay time to 0 seconds, and configure the delayed preemption mode on the master router
by setting a delay time. This allows a transition period for the uplink status and the downlink
status to restore consistency on an unstable network, and thus prevents user devices from
learning the incorrect address of the master router due to dual master routers or frequent
preemption.
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
7 VRRP and VRRP6 Configuration
337